1. Field of the Invention
The invention relates to a plastic vehicle tank for an aqueous urea solution used for reducing the hydrogen oxide content in exhaust gases of an internal combustion engine.
2. Description of the Prior Art
In vehicles operated with diesel fuel, among other needs, the pollutant NOx will have to be reduced considerably, given the impending more-stringent laws on engine exhaust in the next few years. One method that is employed is known as SCR (selective catalytic reduction), in which the pollutant NOx (nitrogen oxides) is reduced to N2 and H2O, with the aid of aqueous urea solution. To that end, the aqueous urea solution is injected upstream of the SCR catalytic converter into the exhaust tube via a metering valve. The aqueous urea solution evaporates in the hot exhaust gas and forms ammonia, which accumulates in the SCR catalytic converter. The ammonia accumulated in the catalytic converter converts the nitrogen oxides contained in the exhaust gas into elemental nitrogen and water vapor. The aqueous urea solution is stored in a tank. This reducing agent makes special demands of the tank. In utility vehicles, the SCR method is already in mass production. It employs tanks of special steel or aluminum. which are heated via the engine coolant.